js/src/zydis/ZydisAPI.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  *
   4  * Zyan Disassembler Library (Zydis)
   5  *
   6  * Original Author : Code taken from examples on zydis github README.md.
   7  *
   8  * Modified by Mozilla.
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in all
  18  * copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  23  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  26  * SOFTWARE.
  27  */
  28
  29 #include <inttypes.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32
  33 #include "zydis/ZydisAPI.h"
  34
  35 void zydisDisassemble(const uint8_t* code, size_t codeLen,
  36                       void(*println)(const char*)) {
  37   ZydisDecoder decoder;
  38   ZydisDecoderInit(&decoder, ZYDIS_MACHINE_MODE_LONG_64, ZYDIS_STACK_WIDTH_64);
  39
  40   ZydisFormatter formatter;
  41   ZydisFormatterInit(&formatter, ZYDIS_FORMATTER_STYLE_ATT);
  42   ZydisFormatterSetProperty(&formatter, ZYDIS_FORMATTER_PROP_FORCE_SIZE, ZYAN_TRUE);
  43
  44   ZyanU64 runtime_address = 0;
  45   ZyanUSize offset = 0;
  46   const ZyanUSize length = (ZyanUSize)codeLen;
  47   ZydisDecodedInstruction instruction;
  48   ZydisDecodedOperand operands[ZYDIS_MAX_OPERAND_COUNT];
  49   char buffer[1024];
  50   while (ZYAN_SUCCESS(ZydisDecoderDecodeFull(&decoder, code + offset, length - offset,
  51                                              &instruction, operands)))
  52   {
  53 #  define LIMIT 48
  54 #  define LIMSTR "48"
  55
  56     // We format the tag and the address and the bytes in a field of LIMIT
  57     // characters and start the menmonic at position LIMIT.  If the
  58     // tag+address+bytes would be too long we put the mnemonic + operands on the
  59     // next line.
  60
  61     // Emit address
  62     sprintf(buffer, "%08" PRIX64 "  ", runtime_address);
  63
  64     // Emit bytes
  65     for (size_t i = 0; i < instruction.length; i++) {
  66       sprintf(buffer+strlen(buffer), "%s%02x", i == 0 ? "" : " ", *(code + offset + i));
  67     }
  68
  69     // Pad with at least one space
  70     sprintf(buffer+strlen(buffer), " ");
  71
  72     // Pad out to the limit if necessary
  73     if (strlen(buffer) < LIMIT) {
  74       char* cur_end = buffer + strlen(buffer);
  75       size_t spaces = LIMIT - strlen(buffer);
  76       memset(cur_end, ' ', spaces);
  77       cur_end[spaces] = '\0';
  78     }
  79
  80     // If too long then flush and provide an appropriate indent
  81     if (strlen(buffer) > LIMIT) {
  82       println(buffer);
  83       sprintf(buffer, "%-" LIMSTR "s", "");
  84     }
  85
  86     // Emit instruction mnemonic + operands
  87     size_t used = strlen(buffer);
  88     ZydisFormatterFormatInstruction(&formatter, &instruction, operands,
  89                                     instruction.operand_count_visible, buffer + used,
  90                                     sizeof(buffer) - used, runtime_address, ZYAN_NULL);
  91     println(buffer);
  92
  93     offset += instruction.length;
  94     runtime_address += instruction.length;
  95
  96 #  undef LIMIT
  97 #  undef LIMSTR
  98   }
  99 }